Fat for Joints
By Jen Christensen
Posted: Tuesday, October 09, 2007 at 10:34 a.m.
Osteoarthritis
Osteoarthritis is a chronic form of arthritis characterized by a
breakdown of the cartilage. Cartilage is the tissue that covers the
ends of the bones in a joint. Its job is to cushion the bones and
prevent them from rubbing against one another during movement.
In osteoarthritis, the cartilage first loses its elasticity,
increasing the risk of damage from trauma or overuse. The cartilage
begins to wear, allowing a small area of the bones to touch and rub
against each other. Over time, as more cartilage wears away, the
affected area of the bone thickens and cysts form under the
cartilage. Tiny growths of bone, called bone spurs develop at the end
of the bone. Pieces of cartilage or bone may break off and float
inside the joint. The lining of the joint (called the synovium) also
becomes inflamed. The damage causes the body to produce enzymes that
further damage the joint cartilage.
According to the Arthritis Foundation, about 21 million Americans
have osteoarthritis. It's the most common form of arthritis. The
condition is most commonly seen in the joints of the hands, spine,
knees and hips. Patients may complain of joint pain, stiffness and
loss of motion in the affected joints.
There is no cure for osteoarthritis. Medications, weight loss,
exercise and joint protection can help reduce the symptoms, but may
not stop destruction of the joint cartilage. When pain can't be
relieved or mobility is severely limited, doctors may recommend
surgery to repair or replace the diseased joint.
Restoring Knee Cartilage
Many areas of the body are able to repair damaged tissue. However,
knee cartilage doesn't have a blood supply, limiting the ability of
the body to repair an injury and restore the tissue. Some physicians
are transplanting specialized cartilage cells, called chondrocytes,
into the damaged area. However, it takes a significant amount of time
for the cartilage to become strong enough to support weight and
normal joint function.
Researchers at the University of Arizona are testing a different
approach to repair knee cartilage, using an implant of stem cells.
Stem cells are a type of unspecialized cell that can self-renew and
have the potential to develop into a specific cell type. Most often,
the cells are retrieved from bone marrow in the hip, using a large
needle drilled into the bone. But scientists have discovered that
body fat is also a rich source of stem cells. A needle can be placed
into the abdomen to retrieve a small amount of fat. The stem cells
are extracted and placed in a special growth medium designed to coax
them into becoming cartilage cells.
The investigators have also developed a special scaffold for the
cartilage cells. The scaffold anchors the implant in the bone and
acts as a support network until the new cartilage cells grow and
become strong enough to bear weight.
Next, the researchers want to place tiny sensors on the scaffold to
measure the effects of various forces (like walking, exercise or
sports) that the knee would need to endure. That information will
help scientists make any necessary design changes in the scaffold.
John Szivek, Ph.D., Orthopaedic Research Director, says the sensors
could help monitor rehabilitation and provide a warning when the
implant is undergoing too much stress.
Currently, cartilage replacement with fat-derived stem cells is still
being tested in a laboratory. Human testing of the engineered
cartilage implant is still awhile away.
AUDIENCE INQUIRY
For general information on osteoarthritis:
Arthritis Foundation, http://www.arthriti
National Institute of Arthritis and Musculoskeletal and Skin
Diseases, http://www.niams.
http://www.hoinews.
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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